OK,
Boom: No a boom is not really necessary, but if you have one it gives you much more control over sail shape. It is easier to control mast rotation (lines come off boom) and you can apply loads of outhaul to flatten the sail when it blows (the amount you can apply with the sliding clew system is necessarily limited). You can also control mast bend better with a boom and it allows you to max your leech tension. However the boat would sail perfectly happily as is. Downwind you wouldn't necessarily need a boom as with the kite up the sail is almost central on the track and sheeted for a close reach.

Bags v. chutes: The general trend is indeed towards chutes. However some people do prefer and use tramp bags. It really is personal preference. Originally, when I spent most of my time two-up we used a Hobie Tiger tramp bag (it's still on the boat even now) but I quickly discovered that when solo it's a no go. You just can't get the kite down quickly (and safely) into a tramp bag on your own. So now we have a chute instead.